Amidation of Bioactive Peptides: The Structure of the Lyase Domain of the Amidating Enzyme

Eduardo E. Chufán, Mithu De, Betty A. Eipper, Richard E. Mains, L. Mario Amzel

Research output: Contribution to journalArticlepeer-review


Many neuropeptides and peptide hormones require amidation of their carboxy terminal for full biological activity. The enzyme peptidyl-α-hydroxyglycine α-amidating lyase (PAL; EC catalyzes the second and last step of this reaction, N-dealkylation of the peptidyl-α-hydroxyglycine to generate the α-amidated peptide and glyoxylate. Here we report the X-ray crystal structure of the PAL catalytic core (PALcc) alone and in complex with the nonpeptidic substrate α-hydroxyhippuric acid. The structures show that PAL folds as a six-bladed β-propeller. The active site is formed by a Zn(II) ion coordinated by three histidine residues; the substrate binds to this site with its α-hydroxyl group coordinated to the Zn(II) ion. The structures also reveal a tyrosine residue (Tyr654) at the active site as the catalytic base for hydroxyl deprotonation, an unusual role for tyrosine. A reaction mechanism is proposed based on this structural data and validated by biochemical analysis of site-directed PALcc mutants.

Original languageEnglish (US)
Pages (from-to)965-973
Number of pages9
Issue number7
StatePublished - Jul 15 2009



ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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